Adjustable stop for brake shoes



June 26, 1934. M. LOUGHEAD Re. 19,225

I ADJUSTABLE STOP FOR BRAKE SHOES v Original Filed Sept. 6, 1927 4 Shets-Sheet 1 June 26, 1934. M. LOUGHEAD 19,225

ADJUSTABLE STOP FORBRAKE SHOES Origihal Filed Sept. 6, 1927 Q 4 Sheets-Sheet 2 June 26, 1934. l LVOUGHEAD v Re. 19,225

ADJUSTABLE STOP FOR BRAKE snoss Original Filed Sept. 6, 192? 4 Sheets-Sheet June 26, 1934. M. LousHElAD 19,225 I ADJUSTABLE STOP FOR BRAKE SHOES Original Fi'led Sept. 6, 192'! 4 Sheets-Sheet :4

ill/MW Ill-L W Reissued ne 26, 1934 ADJUSTABLE STOP FOR BRAKE SHOES Malcolm Loughead, Mokelumne Hill, Calif., as-

signor to Hydraulic Brake Company. Los Angeles, CaliL, a corporation of California Original'No. 1,792,749, dated February 17, 1931,

Serial No. 217,581, September 6, 1927. tion for reissue January 3,

Applica- 1933, Serial No.

17 Claims. (o1. lee-79.5)

My invention relates to improvements in adjustable stops for brake shoes and more particularly to that type of stop employed to limit the retraction of segmental brake shoes or the rigid type, each having one end mounted upon a pivotal support.

An object of the invention is to provide an adjustable stop of the character described which may be simply and accurately adjusted by the manipulation of a single adjustment bolt.

A further object of-the invention is to provide an adjustable stop of the character described,

which after it has been set permits a uniform and predetermined retractive movement of each of the brake shoes. This is important, since when the brakes are applied each shoe may then travel through the same distance in moving to engagement with the brake drum.

A further object of the invention is to provide an adjustable stop of the character described in which means is provided for permitting full outward movement of the shoes into engagement with the brake drum during the application of the brakes, regardless of a decrease in thickness of the brake lining through wear.

Other objects and advantages of my invention will appear more fullyfrom the following description and from the accompanying drawings,- in which similarcharacters of reference indicate similar parts throughout the several views.

Figure l is a side elevation, partly in section, of an internally expanding brake mechanism of the rigid shoe type embodying the adjustable stop;

Figure 2 is a sectional view along the line 2-2 of Figure 1;

Figure 3 is a view 01' a fragmentary-portion of Figure 1, illustrating the operation of the stop with the brake lining worn;

Figure 4 is a view similar vto Figure 1, illustrating a modified form of the adjustable stop;

Figure 5 is a sectional view along the line 5-5 of Figure 4; and Figure 6 is an enlarged fragmentary view of a part of the mechanism illustrated in Figure 4, showing the manner in which the stop is adjusted. In carrying outmy invention, I make use of the ordinary type of rigid shoe, internally expanding brake mechanism consisting of a pair of shoes 1 and 2, each having brake lining 3 carried by the outer faces thereof. v The shoes 1 and 2 are pivotally supported at. their adjacent ends upon a brake shoe mounting pin 4. The pin 4 is secured to the dust pan or rear plate 501' the Figure 1.

brake assembly which is in turn mounted upon the axle housing of the vehicle by bolts 6.

A rigid annular brake drum carried by the vehicle wheel is shown at 7.

Means for moving the shoes 1 and 2 upon their pivotal support 4 to cause the linings 3 to engage with the internal surface of the brake drum 7 is provided in a hydraulic motor consisting of a cylinder 8 and a pair of pistons 9 carried therein, the pistons being connected by operatingrods 10 to the adjacent free ends 11 of the shoes 1 and 2. In my prior Patent, No. 1,468,600, issued-September 18, 1923, I. have fully described the construction and operation of the fluid motor 8.

A tension spring 12 is connected at its opposite ends to the free end of the brake shoes land 2 at 13. Thru the spring exerts a constant force upon the shoes, tending to retract them out of engagement with the drum.

All of the mechanism thus far described is well known in the art and is in use at the present time in the ordinary type of hydraulic brake mechanism.

The present invention relates to an adjustable stop for the shoes and in part consists of a pair ofplates 14 and 15 (see Fig. 2). The plate 14 is oflset so that a portion 16 overlies the adjacent outer portion 17 of the plate 15, the major portions of the plate lying in a common plane and contacting the izmer face of the dust pan or rear faceplate 5.

, Each of the plates 14 and 15 is provided with slots 19 and 20, respectively, for receiving headed guide pins 21 which are securely fixed to the dust pan or rear face plate 5.

- The overlying portions 16 and 17 oi the plates are also provided with slots 22 for receiving a locking bolt 23 which projects through the rear face plate5 and has a threaded nut 24 at the outer end thereof by. means of which the plates 14 and 15 are drawn into close engagement with one another, and movement as between each other and the dust pan or rear face plate 5 thereby is precluded.

Each oi the plates 14 and mounted at its outer end at and 26, respectively.

15 has pivotally 18 stop members 25 Each of the stop plates 25 and 26 has a portion adjacent to its outer end cut away to form an abutment surface-27 tangential to its pivotal support against which pins 28, extending transversely through the shoes 1 and 2,abut when the stopping members are in the position shown in Thus the retractive movement of the shoes, by virtue of the spring 12, is determinable -hythepositlon .osr rthe "h -...80 projecting thrpush a'slot31 inthe lo.

.ottheplates ltandlii which members.

other endotwhichisiastenedto ms (mm 2.. respective1y. and'earried by the Whenthepinsflengagewith theinclined surface the stopping members must move on theircentersliiagainstthetensionotthe springs 29,and thustheliningontheshoeswillproperly engagewiththebrakedrum'i.

Inoperatiomthe unserewingthenutflonthelookingboltfi and pplvins'pressuretotheiiuidmotorshythe adjustable stop is set M springs 61 encompass these portions discs 60 and the iorwardlyext'ending portions 56 of the plates and 51, Thus the stop'members mass InIiguresttoOJhaveflhntratedamodmed form of the invention in which I employ reciprocable stop members in place of the pivoted stop members shown in' the preferred form.-

. 'l 'oithepurposeot'more clearly disclosindthe stop mechanism; I have the spring i2 theshoes l gnd 2 out oiengegement with the In this tom 0'! the invention, platesto and 51 slidably'mounted within a metal channel 52 hioh is drawn toward the rear i'aoe plate 5 by of a bolt 53' and nut 54 which projects the channel ii: and the face plate 5. the

otherandthetaceplatefi."

'l'heplates wand 51 each have elongatedoilset, portions 55 at their adjacent ends whieh ex-- tend across opposite sides of thebolt was shown indottedlinesinl 'iguretsoastosssuremaximum frictional engagement between the plates and the adjacent faces of the channel and rear face plate in the region 0! the bolt where pressure is greatest.

The tree ends oi. the plates 50 and 51' extend forwardly in a'plane, as shown at 56. P rp ndicular to the rear face plate. Redueedportions 57 of reciprocahle stop members. project through -59intheportions58.;Discs80areseeuredtotheinnermost endsoithereduoed'pon tions 5'! o! the stop members. and compression between the 58 are constantly urged inwardly'toward the bolt 53 by the springs 81. Shoulders 63, formed at the Junction of the reduced part and the major ward movement thereof. 7

l'igures4and8,whiohisemployed todraw- The outermost ends oi the stop have.

elongated slots 65 therethrough extending in-the direction oi the brake shoemounting pin 4. The purpose otvproviding elongated slots is to allow for slight variations in the distance between stop -pins 66 projecting transversely through shoes 1 and2andthebraheshoemountingpin. ,sumcient clearaneeisallowedbetweenthepins wandtheadiacentwallsoitheslotststopermit movement of the brake/shoes into and out of twiththe'drum'lp Inadiusting thestopmeehanism. first loosened so that the ;plates 50 and 51 are thrustfto move with respect to other, and thebrakesareappliedsoastoeausethe shoesl andfltomoveagainst'thetensionoi'thespringil.

.The shoes 1 and 2, in moving toward thebrakedrum and carryins'their pins so therewith, cause theplates50 and 51 tomove awayirom the bolt tauponcontaetotthepinstowiththeadiaeent sides of the slots 65. At this timethe springs 61 maintain the Ireciproeable stop members i'uliy retractedwithrespecttothelrplateswand 51.

since the bolt and nut'53 and oflernoresistano'etothemoveme ntottheplates when the brakes have thusbeen applied, the nut5 4istightenedwiththebrakesstillset.-

Whenthebrakesarerelessedtheshoesland fl ret act..byvu-tueorthes ring12,ssistance equal to the elearanoe between the pins -68andtheslots65.

I1,now,thebrakelinings3beeomesoworn N W necess tate engagement of the pins 66 with the nut is 11sportion otthe stop members,'s erve to limit inf the adjacent sides of the slots 65 when the brakes are applied, the brakes are, still free to adequately set by virtue of the springs 61 which Letters Patent is:

1. In a brake of the class described, the combination of a drum, a brake shoe engageable with said drum, means for forcing said shoe against said drum, a stationary support, a lost motion connection between said shoe and'said support in cluding a plurality of relatively movable elements, resilient means tending to prevent lost motion in said connection, said connection being'adapted to limit the retractile movement of said shoe, and releasable means for securing one element of said connection to said support, whereby the position,

of said element may be adjusted by the movement of said shoe transmitted through said connection.

2. In a brake of the class described, the combination with a drum, brake shoes engageable with said drum, means for forcing said shoes against said drum, a stationary support, a lost motion connection between each of said shoes and said support including a plurality of relatively movable elements, resilient means tending to prevent lost motion in said connections, said connections being adapted to limit the retractive movement of said shoes, and releasable means for securing one element of each of the connections to said support whereby the position of said elements may be adjusted by the movement of said shoes transmitted through said connections.

3. An adjustable stop for a vehicle wheel brake shoe comprising stop members, a movable support for said stop members, yielding means for holding the stop members in engagement with the shoe so that the stop member and support will move with the shoe, means for locking the support against movement, and other means forming part of the stop member of the shoe for moving the stop member against said yielding means upon excessive outward movement of the shoe.

4. The combination with the brake shoe of a vehicle wheel brake mechanism, a stop member for engaging with the shoe to limit the retractive movement thereof, a movable support for the stop member, means for yieldingly engaging the stop member with the shoe whereby the stop,

member and support member move when the shoe is applied for adjustment of the stop, and means for locking the support against movement, said stop member being constructed so as to move against said yielding means upon excessive outward movement of the shoe- 5. An adjustable stop for vehicle wheel brake shoes, comprising stop members, movable supports for said stopmembers, yielding means for holding the stop members in engagement with the brake shoes so that the stop members and support will move-with the shoes, for adjustment of the stop members, means for lockingthe supports against movement, and other means forming part of the stop members for moving the stop members against said yielding means upon excessive outward movement of the shoes.

6. An adjustable stop for vehicle wheel brake shoes, comprising stop members, a movable support, said stop members being movably mounted' upon the support. means permitting-the stop members and support to move with the shoes for adjustment thereof, and means for locking the support against movement whereby the stop members. may limit the retractive movement of the shoes, said stop members being formed so as to shift in their relationships with the shoes said shoe with said connection, whereby said connection may be moved to adjusted position by means of said shoe when said connection is free to move relative to said support- 8. In a-device of the class described, a brake drum, a pivotally mounted brake shoe 'engageable therewith, and adjustable means for limiting the retractile movement 01' said-brake shoe comprising a movable stop to positively limit the retractile movement of the shoe, said stop during adjustment being free to move with said shoe, means for releasably clamping said stop in its adjustable position, and other means including a spring associated with the stop for altering the connection between said shoe and said stop upon excessive outward movement of the shoe during brake application as when the shoe has become worn.

9. Brake shoe stop mechanism comprising a brake shoe, a lining therefor, a support for the brake shoe, a member carried by the movable brake shoe, and an adjustable member carried by the brake shoe support, the latter member carrying an abutment for limiting the retractile movement of said brake shoe, said member also having an opposed abutment positioned to be engaged when the brake shoe is in its actuating position, the latter abutment having yielding engagement with said brake shoe, whereby a superior force may cause the brake shoe to move beyond the position of engagement with said 0pposed abutment'as the brake shoe lining wears.

10. A brakehaving, in combination, friction means, 'a guide comprising -a'lever having a part engaged by a portion of the friction means throughout the operation of applying the brake, means for adjusting the position of said guide by shifting the lever while the friction means is in applied position, and means for holding the guide in adjusted position.

11. A brake having, in combination, friction means, a guide engaged by a portion of the friction means-for holding the friction means in adjusted position, holding means for said guide and self-operating means for adjusting the position of said guide when the holding means is released.

12. A brake having a positioning device, in combination with means for holding said device in acfiusted position, and a spring for urging said device in adjusted position when the holding means is loosened;

13. A brake having applying means and a separate positioning device for determining the normal position of a movable brake element, in combination with a spring for urging said device into adjusted position. i

14. A brake comprising a shoe, a positioning device having a lost motion connection with said shoe,andrssilient meansafl'ordinganinereasein 15. A" a shoe. a positioning device, and connection between said 5 shoe snddevioe iorlimited lost movement under normafcpnditions of brake operation; and resilient meansjorallowing a greater lost motion movement upon abnormsl'conditions of brake operation. e I f 'J 10 16. In a brake'shoe positioning device comprisinga pair of members, a lost motion connection therebetween including means for providing a limited free movement between said members,

iepas I andresilient means providing an mum upon an vn i fl b s'mdet rminedi'orce.'

. I iLJn a brake 'shoejpositioninga pair of and a. lost motion connection therebetween having means affording limited tree relative movement, said means including a. yielding abutment onfone of said members, for engaging the other oi said members whereby a predetermined iorcebetwen-said members may increase the lostmotion. above the limited tree relative movement'irovided.

Y P V MALCOLM IDUGHEAD. 

